Automation systems, such as building automation systems for large buildings, generate alarm events. An alarm event may for example represent components in the system which fail (such as a broken sensor) or provide an indication that something is wrong, such as a temperature which exceeds a threshold value. The alarm events are presented to an operator who monitors the automation system in order to allow the alarm events to be attended to.
Traditionally the alarm events are presented in the form of a list. This form of presentation originates from the list of alarms from printers used in the old days. However, since a system may generate hundreds of alarms, lists are not the best way to show alarms in order to make it easy to understand what alarm to act on and relate alarms to each other. In particular, there is a risk that important alarms drown in all information in the list thereby making it difficult for the operator to decide which alarms should be attended to first.
U.S. Pat. No. 7,646,294 recognizes the problems with known alarm lists and suggests representing alarms in a graphical user interface. The alarms are graphically represented by individual colored rectangles. The size, color, luminance and pattern of the geometric shape can define the priority of the alarm. The alarms are grouped into clusters in order to facilitate identification of the root cause of an alarm by spatial pattern recognition. However, although the clustering of the alarms suggested in U.S. Pat. No. 7,646,294 may be advantageous when it comes to analyzing the cause of an alarm it is not useful for allowing an operator to decide which alarms to take care of first. There is thus room for improvements.